Impact tool with chip-resistant striking face



N k L P 1964 H. A. VAUGHAN, JR 3,148,716

IMPACT TOOL WITH CHIP-RESISTANT STRIKING FACE Filed A ril 2, 1962INVENTOR. HOWARD A. VAUGHAN, JR.

United States Patent M 3,143,716 IMPACT TGGL WITH C-RESISTANT STRIKINGFACE Howard A. Vaughan, 3n, Fontana, Wis., assignor to Vaughan &Bushnell Mfg. (10., Bushnell, Ill., a corporation of Illinois Filed Apr.2, 1962, Ser. No. 184,289 1 Claim. (Cl. 14529) The present inventionrelates to portable impact tools and has particular reference to astandard carpenters claw hammer.

As a prelude to a discussion of the present invention, it is to beunderstood that a standard carpenters claw hammer usually has a 16-ouncehead and a handle which is approximately 13 inches in length. Theover-all longitudinal extent or length of the hammer head isapproximately five and one-half inches. Any material deviation fromthese dimensions or from such weight of the hammer head will not betolerated by a carpenter. These dimensions are applicable to hammers ofthe hickory handle type and also to hammers of the so-calledindestructable type wherein the shank portion of the handle is formed ofsteel and is integral with the hammer head. They also are applicable tohammers employing tubular steel shanks. It follows, therefore, that anappreciable amount of steel is involved in the forging of a carpentersclaw hammer, especially a hammer of the indestructible type wherein thehead and shank are integral.

In order that the striking face of the hammer head be of such toughnessas to resist fracturing or spalling and of such hardness as to resistdenting or mushrooming under ordinary circumstances of use, it hasheretofore been found necessary, especially in the better grades ofhammers, to forge the hammer head or the head and shank in the case ofan indestructible type hammer of steel having a high carbon content, forexample, 0.80 carbon steel.

The present invention is designed to overcome the limitation that isattendant upon the quality of steel that may be employed in theproduction of a hammer head to produce a satisfactory striking face, andtoward this end, it contemplates the provision of a hammer head, or inthe case of an indestructible-type of hammer, an integral hammer headand shank wherein a limited portion of the head in the vicinity of thestriking face thereof is separately formed from the main body of thehead and is of a superior grade of chip-resistant steel or alloy toolsteel.

According to the present invention, the separatelyformed portion of thehammer head is in the form of an insert or tip of chip-resistant toolsteel and constitutes an appreciable portion of the impact head properat the forward or striking end of the hammer head. It is of full Widthor diameter in the vicinity of the striking face thereof, but isprovided with a shank which is of reduced diameter and projects with atapered fit into a correspondingly shaped socket in the remaining ormain body portion of the impact head proper, the longitudinal axis ofthe shank of the tip and the socket in the main body portion of the headproper extending in the striking direction of the hammer head as a wholeso that the blows which normally are struck by the hammer will tend todrive the shank of the impact tip into tighter engagement with the wallof the socket which receives it. The insert-like impact tip, when inoperative position on the main body of the hammer head, provides ahammer head which does not depart noticeably in size, shape or weightfrom the size, shape and weight of a conventional hammer head so thatthe hammer as a whole, in the case of a carpenters claw hammer, willmeet the exacting requirements of the experienced carpenter who demands3,148,715 Patented Sept. 15, 1364 that his hammer not only be of corrector accepted proportions, but that it also possesses other less definablequalities such as balance and proper feel.

In United States Patent No. 2,884,969, granted on May 5, 1959 toClarence M. Lay and entitled Hammer Construction with Shock AbsorbingMeans, there has been disclosed a carpenters claw hammer, and inconnection therewith, a full discussion of the requirements of such ahammer has been given. Reference may be had to such patent for a fullunderstanding of these requirements which need not be set forth indetail herein, suffice it to say that thevibrational effects which areset-up in a hammer after impact are not only objectionable to the senseof touch, but they set up stresses in the body of the hammer head in thevicinity of the claw region, which in time crystallizes the metal inthis region so that upon a subsequent occassion when the claws are usedfor leverage purposes or when continued blows are struck, one or bothclaws may break-away from the hammer head. Various means have recentlybeen devised for minimizing vibration in the claw region of a carpentersclaw hammer, and the present invention, in addition to providing achip-resistant hammer of higher quality than has heretofore beeneconomically feasible, also presents vibration-inhibiting qualitieswhich afford an appreciable degree of protection to the claw region ofthe hammer head.

Another phenomenon which is discussed in the aforementioned patent isthat of shock-absorption by means of which there is materially reducedthe tendency of the hammer and through the hammer head body to the clawregion, and then, after a brief period of claw vibration, to return tothe hammer head body and from thence travel along the shank portion ofthe handle to the hand of the user. The present invention in a novelmanner further minimizes the degree of shock or sting which ordinarilyis imparted to the hand of the user of a conventional claw hammer.

A further feature of novelty which is associated with the presentinvention resides in the fact that the means which are employed forinhibiting both vibration in the claw region of the hammer and shock tothe hand of the user also affords a visual means for distinguishing ahammer which is constructed according to the present invention fromhammers not so constructed, this despite the fact that the over-allsize, shape, and weight of such hammers are identical.

Finally, it is an advantageous feature of the present invention that bymanufacturing the impact tip separately from the main body of the hammerhead, as briefly outlined above, the tip may, by reason of itsrelatively small size, conveniently be handled en masse and annealed,quenched or otherwise heat-treated in its entirety bodily as a unit sothat localized operations, such as annealing, hardening, or the like,are eliminated.

The provision of a carpenters claw hammer possessing certain or all ofthe advantageous features briefly outlined above being among theprincipal objects of the present invention, numerous other objects andadvantages will readily suggest themselves as the following descriptionensues.

In the accompanying single sheet of drawing forming a part of thisspecification, one illustrative embodiment of the invention,incorporating the features thereof in a carpenters claw hammer of theindestructible type, has been shown.

In this drawing:

FIG. 1 is a fragmentary side elevational view of a carpenters clawhammer of the indestructible type constructed in accordance with theprinciples of the present invention with certain parts being broken awayin the interests of clarity;

FIG. 2 is an enlarged fragmentary sectional view taken substantiallycentrally and longitudinally through a portion of the hammer head of theimproved hammer; and

FIG. 3 is a sectional view taken on the line 3-3 of FIG. 2.

Referring now to the drawing in detail, and in particular to FIG. 1, theimproved impact tool comprising the present invention has, for exemplarypurposes, been illustrated as being in the form of a carpenters clawhammer of the indestructible type. As shown in the drawing, the hammercomprises a head and a handle. For purposes of discussion herein, it iscontemplated that the hammer is of more or less standard dimensions,i.e., it is provided with a sixteen-ounce head, a thirteen-inch handle,and has a longitudinal spread across the head of five and one-halfinches. While other dimensions and weights are contemplated, the weightsand dimensions above will, if adhered to, provide a hammer which isgenerally acceptable to carpenters and similar tradesmen.

The hammer head has been designated in its entirety by the referencenumeral and is of a composite nature. It consists of two principalparts, namely, a main body portion 11, and a permanently-aifixed impacttip 12, the nature and function of which will be made clear presently.The main body portion 11 of the head is provided with an integral,laterally extending, shank 13 which forms a part of the handle of thehammer. The head 10 in the illustrated form of the invention is of thebell-faced type and includes a cylindrical impact head proper 14 whichis formed in part by the previously-mentioned impact tip 12. The impacthead proper 14 is connected to one side of the medial body region 18 ofthe head 10 by a constricted portion 20 which is polygonal in crosssection. The other side of the medial body region 18 of the head isconnected to a claw region 22, the latter being bifurcated as at 24 toprovide the usual diverging claws 26. The shank 13 merges with themedial region 18 of the head 10 along gradually-formed curved surfaces28 as is customary in the formation of an indestructible-type hammer.The medial body region 18 of the hammer head 10 is provided with arelatively deep socket 36 which is generally rectangular in crosssection and is filled with a vibration dampening substance 32 which maybe wood or a suitable thermoplastic or thermosetting resin.

The shank 13 consists of a proximate grip section 34 and a distalconnecting section 36 by means of which the grip section is operativelyconnected to the medial region 18 of the head 10. The distal section 36is generally elliptical in transverse cross section, the ellipse havinga relatively short minor axis and a relatively long major axis so thatthis section of the shank is relatively thin in the transverse directionof the hammer as a whole. The proximate grip section 34 is generallyflat and the longitudinal side edges thereof are formed with marginalribs 38 so that the section is H-shaped in cross section. The gripsection telescopically receives thereover a tubular sheath 40 which maybe formed of any suitable material but is preferably formed of amaterial having good shock-absorbing qualities, as, for example, anelastomer such as rubber. The shank 13 and the sheath 40 together formthe handle of the hammer.

The arrangement of parts thus far described, with the exception of thepermanently affixed impact tip 12, is substantially the same as thearrangement shown and described in aforesaid Patent No. 2,884,969 and noclaim is made herein to any novelty associated with the lastmentionedarrangement. The novelty of the present invention consists rather of theprovision of the separatelyformed impact tip 12 at the impact end of thehammer head It) and of its association with, and its mode of connectionto, the main body portion 11 of the head of the indestructible-type ofhammer selected for illustration herein.

The impact tip 12 is of mushroom-shape design and includes a generallycylindrical striking head 42 and a relatively short, tapered shank 44.The striking head 42 presents a forward, substantially circular, impactface 46 which merges with the cylindrical side face 48 of the tip on asmall radius as indicated by the reference numeral 50. The thickness,i.e., the axial extent of the striking head 42, is approximatelyone-half of the axial extent of the entire impact head proper 14.

The shank 44 0f the impact tip 12 is tapered on a slant angle ofapproximately 3, and the end face 52 of the shank merges with thefrusto-conical side face 54 on a small radius as indicated by thereference numeral 56. This side face 54 similarly merges with the rearor inner annular face 58 of the striking head 42 on a small radius asindicated by the reference numeral 60.

The tapered shank 44 of the impact tip 12 is telescopically receivedwithin a tapered socket 62 in the forward or front end face 64 of themain body portion 11 of the head 10, the socket 62 being shapedconformably to the shape of the shank 44. A fiber or othershockabsorbing washer 66 surrounds the shank 44 at the base regionthereof and is interposed between the two annular faces 58 and 64. Theimpact tip 12, the washer 66, and the adjacent portion of the main bodyportion 11 of the head 16 are so designed that the composite impact headproper 14 formed by these parts is substantially cylindrical and followsthe contour of the impact head proper of a conventional carpenters clawhammer of correct or acceptable proportions.

The annular end face 64 of the main body portion 11 of the head 10merges with the tapered side wall 68 of the socket 62 on a small radiusas indicated by the reference numeral 70, and the depth of the socket issuch that when the impact tip 12 is driven into position on the end ofthe body portion 11 with the washer 66 in position between the faces 58and 64, there is a small clearance or air pocket 72 between the end face52 of the shank 44 and the bottom face 74 of the socket, this pocketbeing hermetically-sealed by reason of the tightfriction fit between theshank 44 and the side wall of the socket 62.

According to the present invention, the impact tip 12 is formed of thefinest chip-resistant steel obtainable on the market, for example, alloytool steel which is manufactured and sold under the trade named Wizard.

The main body portion 11 of the hammer head 10 is formed of a lowercarbon steel, as, for example, steel having a carbon content as low as.60 or even less. Such a steel is susceptible to the necessary degree ofhardening in the claw region 22 in the case of the illustratedindestructible type hammer, or in the peen region of a machinistshammer, for example. The usual heat-treatment and water or oil quenchingoperations resulting in such localized hardening in the desired regionsmay be resorted to in accordance with conventional practice. The impacttip 12 of special chip-resistant steel may similarly be heat-treated inany desired manner to obtain the necessary degree of toughness towithstand the shock of impact without fracturing or chipping. Thespecific annealing or other heat-treatment operations which areperformed on either the main body portion 11 or the impact tip 12 formno part of the present invention and these operations will be carriedout according to conventional engineering expediencies to impart to theconstituent parts of the composite hammer head 10 the desired over-allor localized physical properties.

In assembling the hammer head 10, the shank 44 of the impact tip 12 isdriven into the socket 62 so as to have a tight friction or drive fittherein. The union thus formed is intended to be a permanent one, anddue to the small slant angle of the mating frusto-conical side face 54and side wall 68, there will be little danger of the impact tip becomingdislodged from the body portion 11. In fact, each blow that is struck bythe hammer when the same is in operation will tend merely to increasethe tightness of the fit.

In the aforementioned Patent No. 2,884,969, the deleterious effects ofthe vibration which is set up in the claw region of the hammer headafter each impact have been outlined in detail, and it has also beenpointed out how the provision of the socket 30 minimizes such vibration.The Washer 66 which is interposed between the two faces 58 and 64 andthe entrapped air within the air pocket 72 absorb some of the impactthat is imparted to the impact tip 12 and further minimizes such harmfuleffects of claw vibration.

As an incidental feature, the washer 66 further provides a means wherebya hammer Which is constructed according to the present invention may bevisually distinguished from conventional hammers having one-piece hammerheads. In the absence of the Washer, the line or seam between thestriking head 42 of the impact tip 12 and the remainder of the impacthead 14 would be indistinguishable. With the washer 66 in position, theimpact tip 12 is clearly visible to an observer.

The invention is not to be limited to the exact arrangement of partsshown in the accompanying drawing or described in this specification asvarious changes in the details of construction may be resorted towithout departing from the spirit or scope of the invention. Therefore,only insofar as the invention has particularly been pointed out ordefined in the accompanying claim is the same to be limited.

Having thus described the invention what I claim as new and desire tosecure by Letters Patent is:

In a claw hammer, in combination, a composite hammer head comprised oftwo principal parts including a main body portion and an impact tip,said main body portion being in the form of a one-piece metallic bodyand including a medial body portion from which there projects forwardlyon one side thereof an impact head proper, and rearwardly on the otherside thereof a bifurcated claw region, said impact head properpresenting a forwardly facing end face and having formed therein aninwardly tapered socket arranged so that its large end intersects saidend face and embodying a frusto-conical side wall surface of small slantangle, said impact tip being in the form of a one-piece chip-resistantmetallic body of tool steel hardened quality and including an enlargedstriking head from which there projects rearwardly a reduced taperedshank having a frusto-conical side surface, the slant angle of which iscommensurate with the slant angle of said side wall surface of thesocket, said shank being press-fitted within said socket, said strikinghead presenting a forwardly facing impact surface, and a washer formedof relatively soft shock-absorbing material surrounding the shank at thebase thereof and interposed between said enlarged striking head and saidforwardly facing end face of the impact head the combined thickness ofsaid washer and the depth of said socket being slightly greater than theaxial extent of said shank whereby a sealed air pocket is created in thebottom region of the socket when the shank is in position therein.

References Cited in the file of this patent UNITED STATES PATENTS147,427 Parker Feb. 10, 1874 561,409 Mann June 2, 1896 1,711,505McCracken May 7, 1929 1,781,344 Salazar Nov. 11, 1930 2,874,738 Lay Feb.24, 1959 OTHER REFERENCES Materials Handbook, 8th Ed. N. Y., McGraw-HillBook Co. Inc., 1956, p. 778-780 Copy in Group 330.

